1. Field of the Invention
The present invention relates generally to electric power lines. More specifically, the invention relates to an apparatus and method for mechanically and electrically disconnecting a service drop power line.
2. Description of Related Art
Power outages not only inconvenience utility customers but may severely damage the utility company's service hardware and any structure attached to the utility lines, as well as creating a hazard with the possibility of dropping a live electrical wire. When such damage occurs, it is often costly for the utility company to repair and replace parts but also costly when such damage causes long delays in restoring power service.
For power outages stemming from the utility companies' efforts to increase energy transmission over existing transmission and distribution lines, some companies have replaced existing conductors with larger ones. This may cause the towers holding such conductors to structurally fail because larger mechanical loads have been imposed upon these towers than intended by their original design. When the towers do fail, the failure may damage or destroy a number of towers, which may cause long delays in restoring power service. To avoid replacing towers to handle the larger loads imposed, various load limiters have been implemented to limit the horizontal component of force to which the tower is subjected. These load limiters allow the power line to drop to the ground when the a particular amount of force is exceeded, thereby avoiding damage to the tower. However, some of these load limiters release the power line prematurely or fail to release the power line after the set amount of force is exceeded. In addition, once the load limiter releases the power line, the entire device must be replaced since the load limiter is not reusable, which is a costly and time consuming ordeal.
A significant number of power outages, however, occur at the service end of the residential power delivery system, i.e., at the service drop power line from the utility transmission or distribution line to a customer's building. For example, such outages may be caused by trees or branches falling on the service drop power line connected to the customer's building. When the tree limb falls on the service drop power line, there is a sudden increase in the tension that may result in damage to the structure and service hardware attached to the building or to the structure and service hardware attached to the utility pole. For example, tension on a service drop power line may pull the standpipe off of the building roof or side and may structurally damage the roof or side as well. Further, tension on the service drop power line may cause damage to a transformer located on the service pole. Moreover, should the service drop power line disconnect from the building, the resulting power line, which could be laying on the ground, may still be energized, thereby causing a potentially dangerous situation. Therefore, there is a need for an improved device to disconnect power lines upon the application of a force sufficient to cause damage to structurally components attached to or holding the power line. Further, there is a need for an improved device with the ability to disconnect one or more multiple power lines in a system having multiple service drop power lines, without disconnecting other non-stressed power lines.